The present invention relates to a nozzle of a stannic furnace which is applied in tin soldering of circuit boards, more particularly, to an adjustable nozzle of a stannic furnace, the caliber of which can be modified.
With the rapid advances in the integrated circuit (IC) packaging technology and the great promotion of operation performance, not only multi-media computers are widely favored by consumers, but also popularization of computers and the related peripheral products are accelerated. However, because of improvements in IC""s operation performance, the number of the packaging contact pins of various components is also greatly increased. This leads that the related circuit board layout design becomes more sophisticated and complicated and that the manufacturing processes for plugging and tin soldering of circuit boards meet with considerable difficulties. In current production procedures in assembly of circuit boards, the manufacturing process for tin soldering the contact pins of the components is mainly by means of wave soldering, wherein the molten liquid tin inside the stannic furnace is gushed up by a pump as a long tin wave and when the circuit board is obliquely transported upwardly through the stannic furnace and makes contact with the tin wave, the liquid tin will enter into the holes where the contact pins of the chip are plugged in the circuit board, fill the tin therein, and form weld spots thereon.
Please refer to FIGS. 1A and 1B, which are schematic diagrams of employing a stannic furnace apparatus 10 to proceed with a process for wave soldering a circuit board 12. The stannic furnace apparatus 10 has a stannic tank 14 for carrying the molten liquid tin therein. A motor pump 16 is mounted in one side of the stannic tank 14 and can gush up the liquid tin within the stannic tank 14. Then, the gushed liquid tin forms a tin wave at a nozzle opening 20 above the stannic tank 14. The circuit board 12 is transported by a slanted delivery track 18 to above the top of the stannic tank 14, and the tin wave gushed up from the nozzle opening 20 of the stannic furnace enters into the holes at the circuit board 12 where the contact pins of the components are plugged, fills the tin therein, and forms weld spots thereon so as to complete the soldering process of the components at the contact pins thereof.
Turning to FIG. 2, which is a schematic diagram of a conventional nozzle of the stannic furnace, the molten liquid tin is full contained within the stannic tank 14 of the stannic furnace 10. When the motor pump (not shown) is motivated, the liquid tin is gushed up from a nozzle pedestal 22 within the stannic tank 14 and is guided through a nozzle tank 23 and then forms the tin wave at the nozzle opening 20 above the nozzle tank 23 so as to carry out the wave soldering process. The nozzle tank 23 is a rectangular tank smaller than the stannic tank 14, and a lower guiding channel 24 at the base of the nozzle tank 23 is mounted on the top of the nozzle pedestal 22. A front backflow stopper 25 and a rear backflow stopper 26 are respectively set at the front and the rear inside the nozzle tank 23, and a structure of the nozzle opening 20 is formed between the two backflow stoppers 25 and 26. The liquid tin inside the stannic tank 14 is spouted out of the nozzle opening 20 above the nozzle tank 23 as a tin wave.
However, in the process of wave soldering the circuit board, the contacting period of the circuit board with the tin wave has much effect in the quality of wave soldering. When the circuit board is wave soldered by the tin waves with different waveforms, the contacting periods of the tin waves with the circuit board would also be different, and certainly this leads to variation in the quality of wave soldering. The most important factor which works upon the waveform of the tin wave is design for the nozzle of the stannic furnace since the waveform of the tin wave spouted out from the nozzle opening is altered once the shape of the nozzle changes. For instance, if the distance between the front and rear backflow stoppers is varied, the waveform of the tin wave produced at the nozzle opening will also change; moreover, if the relative position between the front and rear backflow stoppers in height is varied, the angle and waveform of the tin wave spouted out from the nozzle opening will also change. Therefore, the specification for the nozzle of the stannic furnace in the prior art, including the opening or the relative altitudinal position of the front and rear backflow stoppers, usually must be designed based on the requirements of wave soldering such that the produced waveform of the tin wave is able to conform with the requirements of wave soldering for the circuit board. However, the nozzle of the stannic furnace after design completion cannot be altered or adjusted anymore.
The above-mentioned unfavorable situation is mainly resulted from the fact that the conventional nozzle including the nozzle tank and the front and rear backflow stoppers are fixed on the stannic tank, and thus both the dimension of the nozzle opening and the height positions of the front and rear backflow stoppers are not adjustable. Hence, when wave soldering, it is difficult for the nozzle of the stannic furnace in the prior art to produce an appropriate waveform of the tin wave to meet with the actual requirement, and this causes the contacting period of the circuit board with the tin wave not easy to control and then affects the wave soldering quality of the circuit board.
In view of the aforesaid drawbacks, there is a need in the relevant art for an adjustable nozzle of a stannic furnace so as to control the period when the circuit board contacts with the tin wave and thus to enhance the wave soldering quality of the circuit board.
The primary objective of the present invention is to provide an adjustable nozzle of a stannic furnace. By means of adjustment to the nozzle, an appropriate waveform of the tin wave is produced so as to control the contacting period of the circuit board with the tin wave and the pressure variation of the gushing tin as well as to raise the yield of wave soldering the circuit board.
In one embodiment of this invention, the adjustable nozzle of the stannic furnace comprises a nozzle tank, a front backflow stopper and a rear backflow stopper. A lower guiding groove at the base of the nozzle tank can be linked up with the upper portion of the stannic tank. A rear combining means, which is a bending plate structure is mounted on the backward area inside the base of the nozzle tank. The bending plate is glidingly co-operated with the base of the nozzle tank by means of a horizontal opening. The horizontal opening is a continuous long slot and can be used to adjust the horizontal position of the rear combining means 37 in relation to the base of the nozzle tank and is fixed by a fixing means. The rear combining means is glidingly co-operated with the rear backflow stopper by means of an altitudinal opening. The altitudinal opening is a continuous long slot and can be used to adjust the attitudinal position of the rear combining means in relation to the rear backflow stopper and is fixed by a fixing means. The front backflow stopper is mounted at the forward area inside the nozzle tank. A nozzle opening of the stannic furnace is formed between the front backflow stopper and the rear backflow stopper. After being guided by the nozzle tank, the liquid tin within the stannic tank produces a tin wave at the opening of the nozzle so as to proceed with the tin soldering process.
Since the nozzle of the stannic furnace in the present invention can control the dimension of the nozzle opening by means of adjustment to the location of the rear combining means in the horizontal direction as well as can control the spouting angle of the tin wave by means of adjustment to the altitude of the rear backflow stopper, an appropriate waveform of the tin wave will be produced to control the contacting period of the circuit board with the tin wave and the pressure variation of the gushing tin so as to enhance the quality of wave soldering for the circuit board.